This invention is directed to architectural coating compositions containing certain silicone resins. In particular, it is directed to paints commonly referred to as architectural coatings and/or house paints and stains.
Paints are most often described according to the type of binder or solvent employed. For example, acrylic and alkyd describes the type of binder or resin system used in the paint, whereas latex or water, and oil-based or solvent-based, refers to the type of solvent used in the paint formulation. In the paint industry, the term solvent typically refers to organic hydrocarbon solvents, and does not include water. Most paints are made up of four basic components including a binder or resin, pigments, a solvent, and other additives. Once the paint is applied to a surface, the solvent begins to evaporate, while the binder, pigments, and additives remain on the surface, and form a hard, dry, solid film.
Some examples of binders and resins used in paints include latex emulsions based on acrylic copolymers, vinyl copolymers, as well as styrene copolymers. The type of pigments encompasses organic and inorganic colored pigments, as well as inorganic extender and filler pigments. Additives include compositions such as thickeners, biocides, driers, co-solvents, pigment dispersants, surfactants, defoamers, and other specialty compositions, all present in relatively low levels in the paint formulation.
Water based paints primarily based on acrylic emulsions represent over 70 percent of the architectural coating market. The acrylic latex emulsion based paints are commonly recognized as being the most durable paints for exterior use. Exterior grade paints typically contain copolymers of methyl methacrylate and butyl acrylate or 2-ethylhexyl acrylate. The appearance or finish of paint is a function of its so-called pigment volume concentration (PVC), which ranges from a high of 75 for interior flat paints, to a low of 15 for high gloss enamel. In between are the exterior flat, exterior sheen, interior satin, and semi-gloss finishes. The focus of the present invention is acrylic emulsion containing house paints for interior and exterior applications to wood and drywall.
Silane monomers have been used in water repellent treatments for application to concrete, brick, and wood. They have also been added to acrylic emulsions to improve the weatherability of paints and stains. In such cases, phenyl based silane monomers have been used, or the resins formed by pre-reacting these monomers, i.e., hydrolyzing, since they are considered as being more compatible with the organic moiety of organic resin binders. However, when used as an additive in architectural paint and stains, the water repellent properties of the paint are not consistently improved, meaning they may or may not improve the organic resin binder in the paint. Improving the water repellency of the paint or stain can decrease the water ingress into the substrate, thus increasing the longevity of both the paint and the substrate, and is highly desirable.
It is known that the addition of resins and resin emulsions to paint can improve the water repellent properties across many different types and brands of paint, from flat and high gloss paints to stains. Two other properties that must also be considered when incorporating additives to paints and stains are dirt pick-up and gloss. Silane monomers tend to increase the dirt pick up of the paint, whereas DT, MQ, and MTQ based silicone resins tend to decrease or not affect the dirt pick up of paints. While resins such as MQ type silicone resins can decrease the gloss of paint, since they can form rough films and therefore increase the defects in paints, the MQ type silicone resins can be bodied to reduce the OH content in the resin, that will result in films that have improved gloss, and therefore don't effect the gloss of the final paint.
The DT, MQ, and MTQ silicone resins herein can be emulsified and added to paints as an additive. In addition, they can be added to the resin binder used to make paints before its emulsified and formulated into a paint. When added to an architectural paint, the water repellent properties are improved, in addition to positive effects on dirt pick-up without affecting gloss.
While certain silicone resins have been used in acrylic polymer containing paint compositions such as U.S. Pat. No. 4,446,259 (May 1, 1984), the silicone resins are DMePhTPh type silicone resins, and have the disadvantages noted above. As regards the '259 patent in particular, the paint composition therein containing glycidyl methacrylate is not intended for application to the exterior and interior of homes, but is specially formulated as a paint composition having high heat resistance, i.e., 100-200° C. and above, suitable for application to metal substrates such as pipes, tanks, stacks, and reactors, in large industrial plants and refineries. In addition, it's a solvent-based paint composition, in contrast to the present invention that's an aqueous emulsion based paint composition containing a surfactant.